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vibration frequency analysis Articles

Snecma, part of the SAFRAN group, is dedicated to the production of engines for both air and space. Working alone or in partnership, Snecma designs, develops and produces engines for civil and military aircraft, launch vehicles and satellites. The company is organised in three divisions: Commercial Engines – Snecma and GE Transportation team up to produce the bestselling family of CFM56 ...

In this study, the effect of posture, vibration magnitude and frequency on seat–to–head (STH) and back support–to–head (BTH) transfer functions has been studied under vertical sinusoidal vibration. Twelve healthy male subjects participated in experimental work to measure vertical vibration transmitted to the occupants' heads in three representative postures (erect, ...

An axisymmetric vibration analysis of an isotropic circular plate with a piezoceramic annular plate attached to it is presented. The annular plate is attached at the circular plate edge so that the radius of the circular plate is the inner radius of the annular plate. The piezoceramic annular plate is used as the radial in–plane load source. A free vibration analysis of the plates is presented. A ...

A sophisticated signal processing technique can help to pinpoint bearing failure at an early stage. Chris Hansford, Managing Director at Hansford Sensors, explains. Experienced operators can often tell if a machine is not working properly, on the basis that is does not ‘sound right’. The same principle can be applied – using modern electronics – to identify the exact cause ...

This study investigates the dynamic characteristics and transverse vibration suppression of helicopter rotor blades using centrifugal pendulum vibration absorbers. The governing differential equation of motion of a rotating cantilever beam with a centrifugal absorber is developed using the finite element method and Ritz method. The effectiveness of the developed finite element formulation is ...

Analysis of the vibration responses of a fruit has been suggested as a non-destructive measure of its elastic properties (firmness). In this study, 'Huang gua' melons were excited using three types of balls (wooden, steel and rubber) and the vibration was detected by an accelerometer. The modulus of elasticity of the inner, middle and outer portions of melon flesh were determined using flat plate ...

In this study, a frequency response function (FRF) coupling analysis is presented for a vehicle body and a front axle with four pair of bushings between the two substructures. In order to investigate effects of the rotational stiffness of bushings on the natural frequency estimation, basic formulas are derived and confirmed by using simple beamlike structures. It is illustrated that the natural ...

This paper describes the details of an experimental investigation focusing on the vibration characteristics of a composite fuselage structure of an ultralight unmanned aerial vehicle (UAV). The UAV has a total empty weight of 70.3 kg and 6.3 m in length. The fuselage structure consists of the fuselage body with an integrated vertical stabiliser. All structural components are fabricated from ...

This paper investigates the validity of a hydraulic simulation model to calculate the piston rod acceleration for further frequency domain analysis. At the present time, simulation results analyses of shock absorber characteristics are mostly restricted to the low frequency range for the hydraulic behaviour and the high frequency range for Noise, Vibration and Harshness (NVH) studies. However ...

Non-linear dynamics of a two degrees-of-freedom (TDOF) tuned vibration absorber system using non-linear spring is studied as a boundary value problem. Five different combinations of linear and non-linear springs have been comprehensively analysed. For the different cases, a comparative study is made varying the forcing frequency. Another comparison is made for response versus time for different ...

In this paper, analysis for fault identification in a cracked beam has been carried out. Theoretical, finite element and experimental analyses for identification of the crack depths and their positions in a beam containing multiple transverse cracks are carried out. It has been established that a crack in a beam has an important effect on its dynamic behaviour. The strain energy density function ...

To study the characteristics of the thiophene sulphides in coals, the structures and properties of 4.6–DMDBT were investigated by using density functional theory (DFT) approach in the research, the following results can be illustrated, namely, the geometry parameters, vibration frequencies, total density of states and partial density of states, atomic charges, thermodynamics, Fukui functions, and ...

Cylindrical and spherical shells are largely used in several engineering fields, especially in aerospace vehicles as structural elements and in automotive vehicles as shafts or exhaust and induction systems. Due to their particular relations with vibrations of automotive structures, this work compares various significant shell theories to evaluate the free vibration response. Thin shell theories ...

Nanotechnology is an area which has vast potentials for turning fundamental research into successful innovations. In the present paper, damping in Polyurethane (PU)–Multiwalled carbon nanotube (MWNT) nanocomposites is studied by Dynamic Mechanical Analysis (DMA) and Free Layer Damping (FLD) methods. MWNT is functionalised using ...

The durability of a fan shroud is determined by its vibration response to the road, which in turn is determined by its natural frequencies relative to the frequencies from road excitation. The objective of the current study is to develop an optimisation algorithm that increases a specific structure's natural frequency such that it separates itself from the main band of the road excitation. The ...

The main objective of this study is to present the importance of considering the brake pad surface topography on predicting noise and vibration of braking system through finite element method (FEM). In this paper, a numerical analysis of disc brake squeal using a three-dimensional FE model of an actual disc brake system is presented. Firstly, the FE model is validated using the results of the ...

This paper is concerned with lifetime prediction of components in washing machines. Vibration signals were measured on electric motors during an accelerated lifetime test ranging from 26.7 to 38.5 simulated years. Loose bearings have initiated air-gap eccentricity and rotor-to-stator rubbing, which resulted in a motor breakdown. Significant frequency bands were identified using a spectral ...

Vertical vibration serviceability of an as–built concrete floor, whose 41.55 m span is currently the longest in China, are investigated in this paper by field measurements and numerical analysis. A vibration monitoring system were designed and installed on the floor. Different types of human–induced excitation are simulated such as single person walking, multi–person walking at the same pace ...

In this study, three different active vibration control (AVC) algorithms are implemented and compared in the experimental investigation of gear set shaft vibration control. Apart from feedforward and feedback control system, a hybrid controller is proposed, which is a combination of the adaptive control with filtered-x least mean squares (FXLMS) algorithm and feedback structure with robust ...

The 500 MWe Prototype Fast Breeder Reactor (PFBR) is under construction at Kalpakkam. It is a liquid metal sodium-cooled pool-type fast reactor with all primary components located inside a sodium pool. Fission heat is transferred to a secondary sodium system in an intermediate heat exchanger, which is in turn transferred to water in a Steam Generator (SG). The PFBR-SG is a vertical shell and ...

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